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examples/Multimedia/ICL/ICLCodec/PngScanlineEncoder.cpp

// PngScanlineEncoder.cpp
//
// Copyright (c) 2007-2009 Nokia Corporation and/or its subsidiary(-ies).
// All rights reserved.
// This component and the accompanying materials are made available
// under the terms of "Eclipse Public License v1.0"
// which accompanies this distribution, and is available
// at the URL "http://www.eclipse.org/legal/epl-v10.html".
//
// Initial Contributors:
// Nokia Corporation - initial contribution.
//
// Contributors:
//
// Description:
//
//

#include "PngScanlineEncoder.h"

//
// CPngWriteSubCodec: base class for writing PNG scanlines
//

// Factory function
CPngWriteSubCodec* CPngWriteSubCodec::NewL(const TPngImageInformation& aInfo, const CFbsBitmap* aSource)
        {
        CPngWriteSubCodec* self = NULL;

        switch (aInfo.iBitDepth)
                {
                case 1:
                        self = new(ELeave) CBitDepth1Encoder;
                        break;
                case 2:
                        self = new(ELeave) CBitDepth2Encoder;
                        break;
                case 4:
                        self = new(ELeave) CBitDepth4Encoder;
                        break;
                case 8:
                        switch (aInfo.iColorType)
                                {
                                case TPngImageInformation::EGrayscale:
                                case TPngImageInformation::EIndexedColor:
                                        self = new(ELeave) CBitDepth8Encoder;
                                        break;
                                case TPngImageInformation::EDirectColor:
                                        self = new(ELeave) CBitDepth8ColorType2Encoder;
                                        break;
                                default:
                                        User::Leave(KErrNotSupported);
                                        break;
                                }
                        break;
                default:
                        User::Leave(KErrNotSupported);
                        break;
                }
        ASSERT(self);
        CleanupStack::PushL(self);
        self->ConstructL(aInfo, aSource);
        CleanupStack::Pop(self);
        return self;
        }

CPngWriteSubCodec::CPngWriteSubCodec()
        : iScanlineDes(NULL, 0)
        {
        }

CPngWriteSubCodec::~CPngWriteSubCodec()
        {
        delete iScanlineBuffer;
        delete iPalette;
        }

void CPngWriteSubCodec::ConstructL(const TPngImageInformation& aInfo, const CFbsBitmap* aSource)
        {
        iInfo = aInfo;
        iSource = aSource;
        iScanlineBufferSize = ScanlineBufferSize(iInfo.iSize.iWidth);
        iScanlineBuffer = HBufC8::NewMaxL(iScanlineBufferSize);
        iScanlineDes.Set(&(iScanlineBuffer->Des())[0], iScanlineBufferSize, iScanlineBufferSize);

        // Init stuff specific to derived class
        DoConstructL();
        }

void CPngWriteSubCodec::DoConstructL()
        {
        }

TDes8& CPngWriteSubCodec::Buffer()
        {
        iScanlineDes.FillZ();
        return iScanlineDes;
        }

TDes8& CPngWriteSubCodec::EncodeL(const TInt aScanline)
        {
        if (aScanline < iInfo.iSize.iHeight)
                {
                TUint8* dataPtr = const_cast<TUint8*>(iScanlineDes.Ptr());
                const TUint8* dataPtrLimit = dataPtr + iScanlineBufferSize;

                DoEncode(iSource, aScanline, dataPtr, dataPtrLimit);
                }
        else
                {
                iScanlineDes.Set(NULL, 0, 0);
                }
        return iScanlineDes;
        }

TUint8 CPngWriteSubCodec::ReverseBits(const TUint8 aValue) const
        {
        TUint value = aValue;
        TUint reverseVal = 0;
        for (TInt i = 0; i < 8; i++)
                {
                reverseVal <<= 1;
                reverseVal |= value & 1;
                value >>= 1;
                }
        return TUint8(reverseVal);
        }

void CPngWriteSubCodec::EncodePalettedScanline(TUint8* aDataPtr, const CFbsBitmap* aSource, const TInt aScanline,
                                                                                           const TInt aPixelsPerByte, const TInt aShiftValue)
        {
        // Encode a single scanline with indexes into the current palette
        ASSERT(iInfo.iPalettePresent);
        TPoint pos(0, aScanline);
        const TInt scanLength = iInfo.iSize.iWidth;
        for (TInt i=0; i < scanLength; i += aPixelsPerByte)
                {
                // Pack each byte with 'aPixelsPerByte' index values
                TUint8 pixels = 0;
                for (TInt j=0; j < aPixelsPerByte; j++)
                        {
                        pixels <<= aShiftValue;
                        TRgb rgb;
                        aSource->GetPixel(rgb, pos);
                        pixels |= TUint8(iPalette->NearestIndex(rgb));
                        pos.iX++;
                        }
                *aDataPtr = pixels;
                aDataPtr++;
                }
        }

//
// These classes specialise the PNG writer to write
// scanlines with different bitmap depths/colour types
//

//
// CBitDepth1Encoder
//

void CBitDepth1Encoder::DoConstructL()
        {
        if (iInfo.iColorType == TPngImageInformation::EIndexedColor)
                {
                // Setup palette
                iPalette = CPalette::NewL(2);
                iPalette->SetEntry(0, KRgbBlack);
                iPalette->SetEntry(1, KRgbWhite);
                iInfo.iPalettePresent = ETrue;
                }
        }

TInt CBitDepth1Encoder::ScanlineBufferSize(TInt aPixelLength)
        {
        // 8 pixels per byte
        return ((aPixelLength + KPngDepth1RoundUpValue) / KPngDepth1PixelsPerByte) + KPngScanlineFilterTypeLength;
        }

void CBitDepth1Encoder::DoEncode(const CFbsBitmap* aSource, const TInt aScanline,
                                                                 TUint8* aDataPtr, const TUint8* aDataPtrLimit)
        {
        // Filter method
        PtrWriteUtil::WriteInt8(aDataPtr, iInfo.iFilterMethod);
        aDataPtr++;

        // Pixel data
        const TInt scanLength = iInfo.iSize.iWidth;
        if (iInfo.iColorType == TPngImageInformation::EIndexedColor)
                {
                // Write palette indexes
                EncodePalettedScanline(aDataPtr, aSource, aScanline, KPngDepth1PixelsPerByte, KPngDepth1ShiftValue);
                }
        else
                {
                // Write RGB data
                TInt dataLength = (scanLength + KPngDepth1RoundUpValue) / KPngDepth1PixelsPerByte;
                TPtr8 dataPtr(aDataPtr, dataLength, dataLength);

                aSource->GetScanLine(dataPtr, TPoint(0, aScanline), scanLength, EGray2);

                // Reverse the order of the bits
                while (aDataPtr < aDataPtrLimit)
                        {
                        aDataPtr[0] = ReverseBits(aDataPtr[0]);
                        aDataPtr++;
                        }
                }
        }

//
// CBitDepth2Encoder
//

void CBitDepth2Encoder::DoConstructL()
        {
        if (iInfo.iColorType == TPngImageInformation::EIndexedColor)
                {
                // Setup palette entries
                iPalette = CPalette::NewL(4);
                iPalette->SetEntry(0, KRgbBlack);
                iPalette->SetEntry(1, KRgbDarkGray);
                iPalette->SetEntry(2, KRgbGray);
                iPalette->SetEntry(3, KRgbWhite);
                iInfo.iPalettePresent = ETrue;
                }
        }

TInt CBitDepth2Encoder::ScanlineBufferSize(TInt aPixelLength)
        {
        return ((aPixelLength + KPngDepth2RoundUpValue) / KPngDepth2PixelsPerByte) + KPngScanlineFilterTypeLength;
        }

void CBitDepth2Encoder::DoEncode(const CFbsBitmap* aSource, const TInt aScanline,
                                                                 TUint8* aDataPtr, const TUint8* aDataPtrLimit)
        {
        // Filter method
        PtrWriteUtil::WriteInt8(aDataPtr, iInfo.iFilterMethod);
        aDataPtr++;

        // Pixel data
        const TInt scanLength = iInfo.iSize.iWidth;
        if (iInfo.iColorType == TPngImageInformation::EIndexedColor)
                {
                // Write palette indexes
                EncodePalettedScanline(aDataPtr, aSource, aScanline, KPngDepth2PixelsPerByte, KPngDepth2ShiftValue);
                }
        else
                {
                // RGB values
                TPtr8 dataPtr(aDataPtr, (scanLength + KPngDepth2RoundUpValue) / KPngDepth2PixelsPerByte);
                aSource->GetScanLine(dataPtr, TPoint(0, aScanline), scanLength, EGray4);

                // Reverse the order of the bits
                while (aDataPtr < aDataPtrLimit)
                        {
                        TUint8 value = aDataPtr[0];
                        TUint8 reverse = 0;
                        for (TInt i=0; i < KPngDepth2PixelsPerByte; i++)
                                {
                                reverse <<= 2;  // advance the bits for the reverse value
                                reverse |= value & 0x3; // mask off the 2 bits, then OR with existing reverse value
                                value >>= 2;    // advance the bits for the actual value
                                }
                        aDataPtr[0] = reverse;
                        aDataPtr++;
                        }
                }
        }

//
// CBitDepth4Encoder
//

void CBitDepth4Encoder::DoConstructL()
        {
        if (iInfo.iColorType == TPngImageInformation::EIndexedColor)
                {
                // Calculate palette for image
                iPalette = CPalette::NewDefaultL(EColor16);
                iInfo.iPalettePresent = ETrue;
                }
        }

TInt CBitDepth4Encoder::ScanlineBufferSize(TInt aPixelLength)
        {
        return ((aPixelLength + KPngDepth4RoundUpValue) / KPngDepth4PixelsPerByte) + KPngScanlineFilterTypeLength;
        }

void CBitDepth4Encoder::DoEncode(const CFbsBitmap* aSource, const TInt aScanline,
                                                                 TUint8* aDataPtr, const TUint8* aDataPtrLimit)
        {
        // Filter method
        PtrWriteUtil::WriteInt8(aDataPtr, iInfo.iFilterMethod);
        aDataPtr++;

        // Pixel data
        const TInt scanLength = iInfo.iSize.iWidth;
        if (iInfo.iColorType == TPngImageInformation::EIndexedColor)
                {
                // Write palette indexes
                EncodePalettedScanline(aDataPtr, aSource, aScanline, KPngDepth4PixelsPerByte, KPngDepth4ShiftValue);
                }
        else
                {
                TPtr8 dataPtr(aDataPtr, (scanLength + KPngDepth4RoundUpValue) / KPngDepth4PixelsPerByte);
                aSource->GetScanLine(dataPtr, TPoint(0, aScanline), scanLength,
                        (iInfo.iColorType == TPngImageInformation::EDirectColor) ? EColor16 : EGray16);

                // Swap order of the low/high bits
                while (aDataPtr < aDataPtrLimit)
                        {
                        TUint value = aDataPtr[0];
                        TUint low = value << KPngDepth4ShiftValue;
                        TUint high = value >> KPngDepth4ShiftValue;
                        aDataPtr[0] = TUint8(low | high);
                        aDataPtr++;
                        }
                }
        }

//
// CBitDepth8ColorType2Encoder
//

TInt CBitDepth8ColorType2Encoder::ScanlineBufferSize(TInt aPixelLength)
        {
        return (aPixelLength * KPngDepth8RgbBytesPerPixel) + KPngScanlineFilterTypeLength;
        }

void CBitDepth8ColorType2Encoder::DoEncode(const CFbsBitmap* aSource, const TInt aScanline,
                                                                                   TUint8* aDataPtr, const TUint8* aDataPtrLimit)
        {
        // Filter method
        PtrWriteUtil::WriteInt8(aDataPtr, iInfo.iFilterMethod);
        aDataPtr++;

        // Pixel data
        TPtr8 dataPtr(aDataPtr, iInfo.iSize.iWidth * KPngDepth8RgbBytesPerPixel);
        aSource->GetScanLine(dataPtr, TPoint(0, aScanline), iInfo.iSize.iWidth, EColor16M);

        while (aDataPtr < aDataPtrLimit)
                {
                // Swap the red and blue components of the image data
                TUint8 temp = aDataPtr[0];      // temp = Red
                aDataPtr[0] = aDataPtr[2];      // Red = Blue
                aDataPtr[2] = temp;                     // Blue = temp
                aDataPtr += KPngDepth8RgbBytesPerPixel;
                }
        }

//
// CBitDepth8Encoder
//

void CBitDepth8Encoder::DoConstructL()
        {
        if (iInfo.iColorType == TPngImageInformation::EIndexedColor)
                {
                // Calculate palette for image
                iPalette = CPalette::NewDefaultL(EColor256);
                iInfo.iPalettePresent = ETrue;
                }
        }

TInt CBitDepth8Encoder::ScanlineBufferSize(TInt aPixelLength)
        {
        return aPixelLength + KPngScanlineFilterTypeLength;
        }

void CBitDepth8Encoder::DoEncode(const CFbsBitmap* aSource, const TInt aScanline,
                                                                 TUint8* aDataPtr, const TUint8* /*aDataPtrLimit*/)
        {
        // Filter method
        PtrWriteUtil::WriteInt8(aDataPtr, iInfo.iFilterMethod);
        aDataPtr++;

        const TInt scanLength = iInfo.iSize.iWidth;
        if (iInfo.iColorType == TPngImageInformation::EIndexedColor)
                {
                // Write palette indexes
                EncodePalettedScanline(aDataPtr, aSource, aScanline, KPngDepth8PixelsPerByte, KPngDepth8ShiftValue);
                }
        else
                {
                // Pixel data
                TPtr8 dataPtr(aDataPtr, scanLength);
                aSource->GetScanLine(dataPtr, TPoint(0, aScanline), scanLength, EGray256);
                }
        }

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Copyright ©2010 Nokia Corporation and/or its subsidiary(-ies).
All rights reserved. Unless otherwise stated, these materials are provided under the terms of the Eclipse Public License v1.0.